Datasheet

Robot Control with Distance Detection • Chapter 8
Robotics with the BOE Shield-Bot • 249
Chapter 8. Robot Control with
Distance Detection
In the previous chapter, we used the infrared LEDs and receivers to detect whether an object
is in the BOE Shield-Bot’s way without actually touching it. Wouldn’t it be nice to also get
some distance information from the IR sensors? There is a way to accomplish some rough,
close-range detection with the very same IR circuit from the previous chapter. It’s just
enough information to allow the BOE Shield-Bot to follow a moving object without colliding
into it.
The way is called frequency sweep. Frequency Sweep is the technique of testing a circuit’s
output using a variety of input frequencies.
Determining Distance with the IR LED/Receiver Circuit
This chapter uses the same IR LED/receiver circuits from the previous chapter.
You will also need:
(1) ruler
(1) sheet of paper
 If the circuit from the last chapter is still built on your BOE Shield-Bot, make sure
your IR LEDs are using the 2 kΩ resistors.
 If you already disassembled the circuit from the previous chapter, repeat the
steps in Chapter 7, Activity 1 on page 218.
 Also, make sure to use TestBothIrAndIndicators to verify that the system is
working properly.
 If you are working in different lightging condistions than you were before, use
the IR Interference Sniffer to check for problems.